ATEX 94/9/EC Directive
Groups and zones
Menu |
ATEX 94/9/EC DirectiveGroups and zones
Groups
| Equipment for mines Group I |
||
|---|---|---|
| Firedamp content | Any firedamp content | beyond limiting value |
| Category of equipment which may be used following 94/9/CE directive | M1 | M2 |
| Equipment for surface installations Group II |
||||||
|---|---|---|---|---|---|---|
| Zones | 0 | 20 | 1 | 21 | 2 | 22 |
| Nature of atmosphere | G gas |
D dust |
G gas |
D dust |
G gas |
D dust |
| Explosive atmosphere | Continuously present | Not likely to be present | Accidentally present | |||
| Category of equipment which may be used following 94/9/CE directive | 1 | 2 | 3 | |||
Zones
Hazardous areas for Group II are further divided in zones, these zones relate to the predicted occurrence of when an explosive atmosphere may be present in the area. These zones are defined as being:
Gas
| Color | Zones | Presence of gas |
| 0 | Continuously present (during long periods) |
|
| 1 | Not likely to be present (regular service) |
|
| 2 |
Nota: Drawing and colors are just an example and should not be used for an actual plant, the design of which is the chief architect's responsability.
Dusts
| Color | Zones | Presence of dusts |
| 20 | Continuously present (during long periods) |
|
| 21 | Not likely to be present (regular service) |
|
| 22 | Accidentally present (short-time-service - never in regular service) |
Nota: Drawing and colors are just an example and should not be used for an actual plant, the design of which is the chief architect's responsability.
Types of protection
| Protection symbol | Zones | Description | Symbolic drawing | ||||||
|---|---|---|---|---|---|---|---|---|---|
| 0 | 20 | 1 | 21 | 2 | 22 | ||||
| "c" |  |
|
|
|
Protection by constructional safety according to EN 13463-5 This standard establishes manufacturing requirements which have been proven safe, in order to avoid any inflammation sources such as friction or heating sparks. It applies to apparatus where movement and friction can occur (clutches, brakes, bearings, springs...). |
||||
| "d" | |
|
|
|
Flameproof enclosure Refers to an electrical apparatus whose explosive parts are enclosed in an explosion proof casing. This casing will resist the pressure generated by the internal explosion of an explosive mixture and will prevent the explosion from penetrating to the ambient explosive atmosphere. |
 |
|||
| "e" | |
|
|
|
Increased safety Refers to an electrical apparatus with a high safety coefficient. Such an apparatus is free from excessively high temperatures and, like under normal service conditions, cannot develop inside and outside electric arcs and sparks. |
 |
|||
| "i" | "ia" | |
|
|
|
|
|
Intrinsically safety Refers to a circuit in which neither sparks nor temperature can ignite an explosive atmosphere, if generated under the service conditions specified by the standard regulations (normal and faulty operating conditions). |
 |
| "ib" | |
|
|
|
|||||
| "m" | |
|
|
|
Encapsulation Refers to a special casing in which the parts, of an electrical apparatus which could ignite an explosive atmosphere by either sparking or heating, are encapsulated in a compound in such a way that this explosive atmosphere cannot be ignited. |
 |
|||
| "n" | |
|
Method of protection for electrical equipment designed so that it will not ignite the surrounding explosive atmosphere in normal operation and under certain fault conditions specified in the standard. There are 5 categories of equipment: nA (non-sparking), nC (hermetically sealed), nR (restricted breathing), nL (limited energy) and nP (simplified pressurisation). |  |
|||||
| "o" | |
|
|
|
Immersion Refers to electrical apparatus immersed in oil. |
||||
| "p" | |
|
|
|
Pressurised enclosure Pressurization is maintained against atmosphere by means of a neutral inert gas. |  |
|||
| "q" | |
|
|
|
Refers to a casing containing powder filling. | ||||
Temperature classes
| Group I | |
|---|---|
| Temperatures < 150°C or < 450°C according to coal dust accumulation on equipment |
|
| Group II | |
| Temperature class for gas (G) | Permissible surface temperature of electrical equipment |
| T1 T2 T3 T4 T5 T6 |
450°C 300°C 200°C 135°C 100°C 85°C |
Ignition temperature for dusts
The dust ignition temperature depends on the its consistency and its nature.
The ignition temperatures for various types of dust are available from reference tables: examples
| Dusts | Ignition temperature | |
|---|---|---|
| Clouds | 5 mm layer | |
| Aluminium | 560°C | ≥450°C |
| Charcoal | 520°C | 320°C |
| Coal dust (lignite) | 380°C | 225°C |
| Cocoa | 590°C | 250°C |
| Coffee grounds | 580°C | 290°C |
| Corn | 530°C | 460°C |
| Methyl cellulose | 420°C | 320°C |
| Paper fiber | 570°C | 335°C |
| Phenolic resin | 530°C | >450°C |
| Polyethylene | 440°C | melts |
| PVC | 700°C | >450°C |
| Sugar | 490°C | 460°C |
| Soot | 810°C | 570°C |
| Toner | 520°C | melts |
| Wheat | 510°C | 300°C |
Nota: these temperature information are given as examples and cannot be used as reference table.
All the information about groups, protection type and temperature classes have to be mentioned on the equipment marking
